by Marie Curie 
Da Vinci Notes 17: Friction and the Elements of Machines
Double the weight, double the rubbing, and the face it lies on makes no difference. I found it with blocks, a cord and a pan of lead, and wrote a quarter into every machine.
Leonardo's friction rules two centuries before Amontons: load not area, a quarter of the weight, rollers and bearings, and the Madrid Codex elements of machines.
Leonardo da Vinci
November 8, 2026
28 min